While the posted patch is minimal and exits loudly on all write errors, here's a patch which I'll be using in my own windows build, which tries to detect a SIGPIPE-like scenario, by testing that outputBuff is stdout (cout), and that stdout is a pipe (in C, because I don't know how to do that in C++).

If it detects a write error to a pipe, then it exits quietly with code 128+SIGPIPE:

diff --git a/lib/srchilite/bufferedoutput.cpp b/lib/srchilite/bufferedoutput.cpp
index 18e614e..664bab2 100644
--- a/lib/srchilite/bufferedoutput.cpp
+++ b/lib/srchilite/bufferedoutput.cpp
@@ -4,10 +4,14 @@
 // Copyright: See COPYING file that comes with this distribution
 //

+#include <sys/stat.h>
+#include <iostream>
+
 #ifdef HAVE_CONFIG_H
 #include "config.h"
 #endif

+#include "ioexception.h"
 #include "bufferedoutput.h"

 namespace srchilite {
@@ -26,6 +30,22 @@ void BufferedOutput::output(const std::string &s) {

     if (alwaysFlush)
         outputBuff << flush;
+
+    if (outputBuff.bad()) {
+        struct stat sb;
+
+        if (&outputBuff == &cout &&
+            fstat(1, &sb) == 0 &&
+            (sb.st_mode & S_IFMT) == S_IFIFO)
+        {
+            // write error to outputBuff, which is cout, which is a pipe.
+            // likely a SIGPIPE case, on a system without it - like windows.
+            // emulate SIGPIPE quietly.
+            exit(128 + 13);  // 128+SIGPIPE
+        }
+
+        throw IOException("cannot write", "");
+    }
 }

 void BufferedOutput::postLineInsert(const std::string &s) {

It would be nicer to do that in pure C++, and possibly even detect the case more accurately, but I don't know how to do that.

I can test patches on windows though, if you have other suggested solutions.